JPH1110710A - Extrusion molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry properly raw material pellets sufficiently in compliance with the increase of the diameter of a screw and knead without increasing extremely the molten resin pressure by improving the shape of the screw. SOLUTION: Raw material pellets fed from a hopper are carried forward as solids while the postures are tilted by flight channels on a hopper ground zone as a force cooling zone for a cylinder on a feed section B and deep flights of the channel depth h1 of a first screw 11 on the feed section B of a screw 10, and the intervals between raw material pellets are contracted slightly and successively on a screw section of tapered flight channel depth. At that time, a barrel section in the vicinity of the hopper ground zone is cooled naturally. The temperature of the barrel section, therefore, is approximately in the range from the room temperature to the softening temperature for the pellets to be used. The surfaces of respective particles of the raw material pellets, therefore, are softened slightly at the time of being carried as solids, and carried to a melt accelerating section C without being cooled and cured forcibly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extruder.

[0002]

2. Description of the Related Art In an extruder of this type, a raw material pellet made of synthetic resin is supplied into a cylinder from a raw material pellet supply port, and the raw material pellet is not rotated in the cylinder by the rotation of the screw. In particular, a hopper gland region in which several square grooves are engraved in parallel in the axial direction is disposed near the raw material pellet supply port, and the bottom of these square grooves is closer to the downstream side. It is formed shallow (see Japanese Utility Model Application Laid-Open No. 58-62623).

[0003]

Generally, there are various shapes of raw material pellets, such as a spherical shape, a cylindrical shape, a square disk shape and the like, and the sizes thereof are various in size, and the hardness is hard and soft. If a plurality of types of hopper ground areas having the above-mentioned square grooves are prepared according to the resin raw material pellets, the cost increases. In order to avoid this high cost, a common hopper ground area is usually used regardless of the type of raw material pellets. However, when a common hopper ground area is used, the square groove dimensions are formed so as to be suitable for transferring a specific raw material pellet, so that the specific raw material pellet has a smaller size or a different shape. When trying to transfer the material pellets, the raw material pellets are fitted into the square grooves, and the raw material pellets only roll in the square grooves, and the rotation of the screw cannot transfer the desired amount of raw material pellets in the extrusion direction. As a result, the amount of the discharged resin becomes insufficient, and extrusion molding, inflation molding or blow molding may become impossible. Further, when the raw material pellets are soft, the raw material pellets are divided in the rotation direction of the screw at the corners of the square grooves, and have a small size, and a desired amount is obtained by rotating the screw similarly to the small raw material pellets. In some cases, the raw material pellets cannot be transferred.

[0004] In order to solve the above-mentioned problem, the groove in the hopper gland area is formed into a special shape and the groove is formed in a flat 4-1.
As disclosed in Japanese Patent No. 35316, when the diameter of the screw is small, the transfer amount of the raw material pellets can be sufficiently ensured, but when the diameter is increased, the raw material pellets tend to slip. The present invention provides an extrusion molding machine that improves the shape of the screw, sufficiently copes with the increase in the diameter of the screw, appropriately conveys the raw material pellets, and enables kneading without extremely increasing the pressure of the molten resin. The purpose is to provide.

[0005]

In order to solve the above problems, a specific invention is directed to a hopper gland region of a cylinder in an extruder, wherein a screw of a screw has a groove depth from a rear end to a front end of the hopper gland region. An extruder having a tapered portion that becomes shallower.

In order to solve the above-mentioned problem, the length of the screw in the hopper gland area of the extruder is at least three pitches from the center position of the hopper, and of the three pitches, the length of the screw is two pitches from the center position of the hopper. It is desirable that the groove depths be the same, and that the taper be formed so that the taper becomes shallower as the groove depth of the remaining one pitch becomes progressively more forward as it goes forward than the groove depth of the two pitches.

In order to solve the above-mentioned problem, the screw in this extruder includes a supply section, a melting promoting section, a homogeneous section, and a metering section from a hopper gland region of a cylinder to an outlet of the extruder. A first screw is formed from the supply section to the central portion of the melting promoting section, and a second screw having a pitch smaller than the pitch of the first screw is formed in the remaining portion of the melting promoting section, The first screw and the second screw are separated from each other by a predetermined dimension, and a kneading portion is formed at the separated portion. The first screw is connected to the supply portion of the hopper gland region and the melting promoting portion near the separated portion. The groove depth of the middle portion is formed to be shallower than the groove depth located at each position, and the groove depth of the communicating portion between the deep portion of the groove depth and the remaining portion is tapered. It is characterized by:

In order to solve the above-mentioned problem, the length of the first screw in the extruder is at least 13 pitches from the center of the hopper. Three pitches are located from the center position, and the groove depth of two pitches is fixed from the center position of the hopper, and the groove depths of two pitches following this are shallower as the groove depths of the two pitches are sequentially moved forward. The groove depth of the two pitches following the tapered portion is smaller than the pitch depth of the two pitches from the center of the hopper and is constant, and the pitch of the two pitches following the shallow portion of the groove depth is constant. The groove depth is formed in a taper that becomes deeper as it goes forward, and the remaining five pitches of the groove depth following the tapered portion are constant and It is preferably in the said being two pitches groove depth and the same or slightly deeper from the position.

In order to solve the above problem, a spiral groove having the same pitch as the pitch of the first screw of the screw in the extruder is formed in the hopper ground area. The ratio h / D of the groove depth h to the screw diameter D is 0.11 to 0.12 in the supply portion corresponding to the hopper gland region and in the portion located in the fusion promoting portion on the separation portion side. The ratio h / D in the part is preferably 0.09 to 0.093.

In order to solve the above-mentioned problem, it is preferable that the ratio of the pitch of the second screw to the pitch of the first screw in the extruder is 0.77 to 0.85.

In order to solve the above-mentioned problem, it is preferable that the size of the separation portion in the extruder is 8 to 10 mm. In order to solve the above problems, the diameter of the screw in the extruder is set to 50 mm to 90 mm.

In order to solve the above-mentioned problem, the pitch of the first screw of the screw in the extruder is the same as that of the first screw, and the spiral groove is formed in a reverse screw relationship with the first screw. Formed in the hopper ground area,
The hopper gland region is a forced cooling region, and the barrel portion located in the vicinity of the hopper gland region in the pellet transfer direction is a natural cooling region.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Claims 1, 2, 3, 4, 5, 6,
Representative embodiments of the inventions described in 7, 8, and 9 will be described. 1 to 4, A indicates the entire extruder,
The screw 10 in the extruder A is fed from the hopper gland area G of the cylinder 15 to a die (for example, a forming die for inflation film forming) 20 connected to the discharge port of the extruder A, and the supply unit B It includes an accelerating part C, a homogeneous part D, and a measuring part E. A first screw 11 is formed from the supply part B to the central part of the fusion promoting part C. A second screw 12 having a pitch P2 narrower than the pitch P1 of the first screw 11 is provided in the remaining portion of the fusion promoting portion C.
Are formed. The first screw 11 and the second screw 12 are separated from each other by a predetermined size (for example, 10 mm). A kneading portion F is formed in the separated portion 13. Groove depths h located at the supply section B and the melting promoting section C near the separation section 13 respectively.
The groove depth h2 of the intermediate portion is formed to be shallower than that of 1. The groove depth of the communicating portion between the deep portion and the shallow portion is tapered.

More specifically, in the hopper gland region G of the cylinder in the extruder A, the first screw 11 of the screw 10 has a groove depth h whose front end is larger than the rear end of the hopper gland region G. It has a tapered portion that becomes shallow. More preferably, the length of the screw 10 in the hopper ground area G is at least three pitches of the first screw 11 from the hopper center position G1, and of these three pitches, the groove depth is two pitches from the hopper center position. The depth h1 is the same, and the groove depth of the remaining one pitch is formed to be shallower and tapered as going forward from the groove depth h1 of the two pitches, and becomes the groove depth h2 of the intermediate portion. The length of the first screw 11 is 13 pitches from the center of the hopper, and three pitches are located from the hopper center position G1 among these 13 pitches corresponding to the hopper grant area G. The groove depth of two pitches from G1 is constant, and the groove depth of the following two pitches is formed in a taper that becomes shallower as it goes forward in order from the groove depth of the two pitches. The groove depth of the two pitches following the hopper center position is shallower than the groove depth of the two pitches from the center of the hopper and is constant, and the groove depth of the two pitches following the shallow portion of the groove depth is:
The taper is formed in a taper that gradually becomes deeper as it goes forward, and the groove depth of the remaining five pitches following the tapered portion is constant, and is formed to be equal to or slightly deeper than the groove depth of two pitches from the hopper center position. ing.

The first screw 1 of the screw 10
1 having the same pitch as the pitch P1, and having a triangular cross section,
Spiral groove G in a relationship between the first screw 11 and the reverse screw
6 to 8 are formed in the hopper ground area G. This hopper ground area G is a forced cooling area,
The barrel portion G3 located near the hopper ground region G in the pellet transfer direction is a natural cooling region. In the first screw 11, the ratio h / D of each groove depth h1, h2 and the screw diameter D is h1 / D = h1 / D =
0.11 to 0.12, and the ratio h2 / D in the intermediate portion is preferably 0.09 to 0.093. Second screw 1 with respect to pitch P1 of first screw 11
The ratio P2 / P1 of the pitch P2 of 2 is set to 0.77 to 0.85. The distance 13 is 8 to 10 mm in size,
The screw diameter D is 50 mm to 90 mm.

Extruder A at the end of the cylinder 15
A forming die 20 is provided to be freely connected to the discharge port.
This die 2 is located near the annular discharge port 21 of the molding die 20.
An air ring 32 having two upper and lower annular outlets 30 and 31 concentrically with 0 is provided. The outer lip of the lower annular outlet 30 near the annular outlet 21 is a lower end portion 41 of the bubble-side inclined inner surface 41 of the high annular block 40.
a. The bubble-side inclined inner surface 41 is an annular inner surface whose diameter increases toward the upper end for guiding the air flow along the entire outer peripheral surface of the bubble B. An inner lip 33 of the upper annular outlet 31 is formed at the upper end of the annular block body 40, and the tip of the inner lip 33 of the upper annular outlet 31 extends in the bubble B flow direction (outside). Are killed along.

Of the outer lips 33 and 34 forming the upper outlet 31, the tip of the outer lip 34 is bent inward toward the inner lip 23, and the outer peripheral surface of the outer lip 34 Auxiliary lip 3 with adjustable vertical movement
5 and the outer lip 34 and the auxiliary lip 35
An annular pressure chamber 36 having a variable capacity is formed between the pressure chambers 36 and 36 so as to open toward the bubble B side.

A cylinder 37 extending above the rectifying pressure adjusting chamber 36 is provided above the air ring 32, and a chamber 38 communicating with the outside air is formed between the cylinder 37 and the air ring 32. An auxiliary valve guide 39 is provided at the upper end of the cylindrical body 37 so as to be vertically movable. A horizontal ridge line 43 is formed in an upper and lower hierarchy by adjacent depressions 46 formed in steps on the inclined inner surface 41 of the block body 40, and an extension line connecting these ridge lines 43 forms a guide surface of the valve B. I have. The outer surface of the annular block body 40 on the side opposite to the bubble is a substantially vertical surface 44 and an annular vertical wall 48 having an outer lip 34 of the upper annular outlet 31 at the upper end and an annular outlet 31 at the upper end.
Is formed at a connecting portion between the first horizontal annular air passage 46 communicating with the blower P and the vertical annular air passage 45. The divergent and divergent air flows toward the annular block body 40 to form an air rectification / pressure adjustment chamber 47. The first horizontal annular air passage 46 is formed between an annular horizontal wall 49 having the annular vertical wall 48 at the inner end and an annular substrate 50 having the lower annular outlet 30 at the inner end. I have. A horizontal second annular air passage 51 branched from the rectification / pressure adjustment chamber 47 communicates with the lower annular outlet 30. This horizontal second annular air passage 5
1 is formed between the bottom surface 40 a of the annular block body 40 and the annular substrate 50. The air ring 32
An auxiliary air ring (not shown) is arranged at a distance above.

The operation of the extruder A will be described as applied to inflation film molding. When the screw 10 is rotated, the raw material pellets supplied from the hopper are supplied to the supply section B at the groove 61 of the hopper ground area G of the cylinder 15 and the groove depth of the first screw 11 at the supply section B of the screw 10. With the deep flight of h1, the solid is transferred forward while tilting its attitude,
The gap between the raw material pellets is gradually reduced in the tapered portion where the groove depth becomes shallower from the rear end to the front end of the hopper ground area. At this time, the pellets are forcibly cooled in the hopper gland region G, and the barrel portion G3 near the hopper gland region G is naturally cooled. That is, the heat transferred from the melting promoting portion C is naturally cooled in the barrel portion G2. The temperature of the barrel portion G3 ranges from room temperature to the softening temperature of the pellet used. Therefore, when transferring solids,
The raw material pellets are sent to the melting promoting section C without being forcibly cooled and hardened to the extent that the surface of each particle softens slightly.

Next, in a flight portion having a shallow groove having a groove depth h2, which is an intermediate portion of the first screw 11, the gap between the raw material pellets is further reduced slightly between the inner wall of the cylinder 15 and the screw 10, and In the state where the gap between the pellets is reduced, the raw material pellets are transported forward again by the deep flight of the first screw 11 having the groove depth h1 near the separation portion 13 with a fusion area slightly larger than the intermediate portion. Then, the forward transfer is temporarily interrupted in the separating section 13, and after kneading, the flight of the second screw 12 further promotes the melting of the raw material pellets. Thereafter, the molten resin is extruded from the discharge port of the extruder A to the die 20 through the homogenizing section D and the measuring section E in the same manner as in the known art. When the single blower P is started, the cooling air is blown out from the two upper and lower blowout ports 30 and 31, and the bubble B is pushed out from the annular discharge port 21 of the die 20.

The cooling air blown out from the lower outlet 30 of the air ring 32 preliminarily cools the molten resin extruded from the annular discharge port 21 of the die 20 in the vicinity of the circular discharge port and presolidifies the resin. The melt tension is increased to such an extent that the stretching ratio is not impaired. After performing the preliminary cooling, the air flows at a high speed in the bubble flow direction through a gap between the outer surface of the bubble B, which is expanded and molded by the internal pressure, and the bubble-side inclined inner surface 41 of the block body 40. The bubbles flow into and diffuse into the step-shaped depressions 42 of the bubble-side inclined inner surface 41 to reduce the wind velocity. The balance between the internal pressure in the depressions 42 and the internal pressure of the bubbles B allows the bubbles B having a low melting tension to be removed from the lower stage. The block body 4
0, which is lifted and supported from the outside without making surface contact with the inclined inner surface 41 on the bubble side, eliminates its drooping, and its low wind speed reduces its vibration, thus completely preventing the generation of wavy slack on the surface of the bubble B. I do. The air that has flowed into the dent 42 and temporarily stays therein is cooled by the cooling airflow blown out from the lower outlet 30 of the air ring 32.
2 and a part of the air successively flows along the air flowing along the bubble and flows out from the dent 42 toward the upper outlet 31 side. To maintain.

The speed of the cooling air flow blown out from the lower outlet 30 is rapidly reduced by the flow of the air flow into each recess 42, and the flow speed is further reduced by mixing and extruding the air from the recess 42. Also, the speed of the air flow in the gap between the outer surface of the bubble B and the tip surface of the outer lip 33 of the lower outlet 30 is also reduced, and the degree of the Venturi effect generated by this air flow is not increased so much. There is no possibility that the bubble B comes into contact with the front end surface of the outer lip 33, and there is no possibility that the wall B will be unevenly molded.

Next, the air flowing out to the upper-stage outlet 31 merges with the air blown out from the upper-stage outlet 31 to further cool the bubbles, and from the outside in the rectification pressure adjusting chamber 36. While being blown from the chamber 38 toward the bubble B, the auxiliary air guide 39 increases the blow ratio of the bubble, stabilizes the bubble, and stabilizes the bubble. The resin is stably formed with a wide width and substantially the same stretching ratio in the vertical and horizontal directions without contacting the auxiliary lip 35 with a high blow ratio.

Further, the cooling air flow supplied from the blower is branched into the lower outlet port 30 and the upper outlet port 31 in the block body 40 and formed on the outer surface of the block body 40 on the side opposite to the bubble. The cooling air flow supplied to the upper-stage outlet 31 through the vertical annular air passage 45 is spread horizontally toward the block 40 near the lower end of the vertical annular air passage 45. After rectification and pressure adjustment in 46, a cooling air flow having a constant pressure is blown out from the entire area of the upper outlet 31 to stably support and blow the entire circumference of the bubble B, thereby reducing the pressure loss. When changing the blow ratio, the auxiliary lip 35
When the height of the auxiliary bubble guide body 39 is changed, the volume of the rectification pressure adjusting chamber 36 is changed, the amount of air blown out of the chamber 38 is adjusted, or the opening area of the chamber 38 is increased. Adjust vertically.

[0025]

According to the specific invention, in the hopper gland region of the cylinder in the extruder, the screw of the screw has a tapered portion whose groove depth becomes shallower from the rear end to the front end of the hopper gland region. Therefore, the raw material pellets can be transferred to the front in a solid state even when the rotation power of the screw is low, without slightly reducing the gap between the raw material pellets irrespective of the screw diameter.

In the invention according to claim 2, in addition to the effect of the specific invention, the length of the screw in the hopper gland region of the extruder is at least three pitches from the center position of the hopper, and the length of the screw is three pitches. Of these, the groove depth of two pitches from the center of the hopper is the same, and the groove depth of the remaining one pitch is formed in a taper that becomes shallower as going forward from the groove depth of the two pitches. During the solid transfer, the gap between the raw material pellets can be surely slightly reduced.

The invention described in claim 3 is the first or second invention.
The following effects are obtained in addition to the effects of the described invention. The screw in the extruder includes a supply section, a melting promoting section, a homogeneous section, and a metering section from the hopper gland area of the cylinder to the discharge port of the extruder, and a first section from the supply section to the center of the melting promoting section. In the remaining portion of the fusion promoting portion, second screws having a pitch smaller than the pitch of the first screws are formed.
The second screw is separated from the second screw by a predetermined dimension, and a kneading portion is formed at the separated portion. The first screw is connected to the supply portion corresponding to the hopper gland area and the melting promoting portion near the separated portion. It is formed so that the groove depth at the middle part is shallower than the groove depth at which it is located, and the groove depth of the communicating part between the deep part and the shallow part of the groove is tapered. Therefore, the raw material pellets can be solid-transferred by reducing the gap between the raw material pellets in the axial direction of the screw by the flight of the first screw in the supply unit in the hopper gland area, and the intermediate part is located near the separated part. Without increasing the cylinder internal pressure with the expansion of the molten cross-sectional area in the part where the groove depth of the part located in
The subsequent melting and transfer of the raw material pellets can be carried out smoothly, and the load applied to the screw, that is, the driving motor thereof can be reduced as compared with the conventional method in which the raw material pellets are transferred over the entire supply section with a constant groove depth of the screw. In addition to this, the semi-molten raw material pellets are then kneaded with the first screw in the melting promoting portion at a separation portion which is a cut portion of the second screw, and the second screw is kneaded.
When the kneaded resin is further melted by the screw flight and transferred to the homogeneous section and the measuring section, the raw material pellets can be kneaded homogeneously, and when the same transfer force as that of the conventional extruder is used, the The throughput can be higher than conventional. In addition, the raw material pellets in the supply unit reduce the gap between the raw material pellets during the transfer, and by providing a kneading unit in the melting promoting unit, compared with the case where the raw material pellets are intensively melted in the melting promoting unit. Deterioration of the molten resin can be suppressed, and by suppressing this deterioration, the discharge amount can be increased as compared with the conventional one.

In the fourth aspect of the present invention, the first
The length of the screw is set to a dimension of at least 13 pitches from the center of the hopper. Corresponding to the hopper grant area, three of these 13 pitches are located from the center position of the hopper, and two pitches from the center position of the hopper. The depth is constant, and the subsequent two-pitch groove depth is formed in a taper that becomes shallower as it goes forward ahead of the two-pitch groove depth, and a two-pitch groove following the tapered portion is formed. The depth is shallower than the two-pitch groove depth from the center position of the hopper and is constant. The two-pitch groove depth following the shallow part of the groove depth is formed into a taper that becomes progressively deeper as it goes forward. The groove depth of the remaining 5 pitches following the portion formed in the hopper is constant, and is formed to be the same as or slightly deeper than the groove depth of 2 pitches from the hopper center position. Because of Te, without increasing the length of the first screw, it can exhibit the effect of the invention of claim 3, wherein. In particular, by connecting the portions of the first screw having different groove depths with the tapered portions of the groove,
The transition from the step of reducing the gap between the raw material pellets to the melting promotion step can be performed smoothly, and the retention of the raw material pellets,
It can be discharged to a die as a homogeneous molten resin without deterioration.

According to the fifth, sixth and seventh aspects of the present invention,
The above effect is further enhanced. More specifically, in the fifth aspect, in addition to the effects of the third and fourth aspects, in the first screw, the ratio h / D between each groove depth h and the screw diameter D is the same as the above. 0.11 to 0.1 in the supply part and the melting promotion part corresponding to the hopper gland area
2, and the ratio h / D in the intermediate portion is 0.09.
The gap between the raw material pellets can be appropriately reduced at a position where the depth of the groove in the intermediate portion is small, but the ratio h / D of the groove depth h and the diameter D of the screw can be appropriately reduced. By specifying D as described above, the raw material pellets in which the gap between the raw material pellets is reduced can be melted and transferred to the deep groove portion in the melting promoting portion without increasing the load, and the solid Transfer and melt mixing can be performed under low load. If the upper limit of the numerical value is out of the range, clogging of the raw material pellets is caused. If the lower limit is not exceeded, the gap between the raw material pellets cannot be sufficiently reduced and the raw material pellets cannot be sufficiently melted.

According to the sixth aspect of the invention, the effects of the third, fourth and fifth aspects of the invention are added. The ratio of the pitch of the second screw to the pitch of the first screw is from 0.77 to
Since the ratio is set to 0.85, the solid transfer in the supply unit can be smoothly performed by the first screw, and the melting of the raw material pellets can be promoted more than a part of the first screw and the second screw.

According to a seventh aspect of the present invention, in addition to the effects of the third, fourth, fifth, and sixth aspects, the size of the separation portion is set to 8 to 10 mm. An appropriate kneading portion can be formed in the portion. If the value is outside this range, the effect of the separated portion cannot be exerted, and the portion becomes a pool for the molten resin, and the burden on the downstream homogeneous portion increases.

In the invention according to claim 8, the conventional technology can be applied only to those having a screw diameter of 50 to 55 mm. Diameter 50-90
mm, the effect of the invention according to claims 3, 4, 5, 6, and 7 can be exhibited. Using the screw, LLDPE raw material pellets are extruded by the metallocene catalyzed method, and when blown film is formed, the raw material pellets are transferred to a solid without increasing the motor load, which is more than when a conventional full-flight screw is used. , 1.2 to 1.5 times the amount of extrusion per unit time can be increased, and if the amount of extrusion is the same, the length of the cylinder and screw can be shortened, and the heating time can be shortened. .

According to the ninth aspect of the invention, in addition to the effects of the first, second, third, fourth, fifth, sixth, seventh and eighth aspects, the pitch of the first screw of the screw is the same as that of the first screw. A spiral groove is formed in the hopper gland region in a reverse screw relationship with respect to the first screw, and the hopper gland region is a forced cooling region. Since the barrel portion located is characterized as being a natural cooling area, the surface of the raw material pellet is slightly softened in the barrel portion communicating with the hopper gland area, accompanying the hardening of the raw material pellet during solid transfer. The raw material pellet supplied from the hopper is melted smoothly by the spiral groove and the flight of the first screw without causing damage to the flight and increasing the solid transfer force. It can be supplied to the advance unit.

The effect common to the above claims is that the raw material pellets are not suddenly increased in the barrel internal pressure when moving from the hopper gland region to the melting portion, and the barrel internal pressure in the melting portion is kept almost constant. In addition, the raw material can be melted, and the load applied to the screw of the raw material pellet can be reduced. In other words, the raw material pellet can be semi-forced transferred. The effect when applied to the inflation film molding in the embodiment is that, after pre-cooling, the air is expanded by the internal pressure and the outer surface of the bubble B and the block body 40 are expanded.
Flows at a high speed in the bubble flow direction in the gap with the bubble-side inclined inner surface 41, and a part thereof flows into and diffuses into the step-shaped depression 46 of the inclined inner surface 41 to reduce the wind speed, and to reduce the wind speed. Due to the balance between the internal pressure and the internal pressure of the bubble B, the bubble B having a low melt tension is removed from the lower block body 4.
0, which is lifted and supported from the outside without making surface contact with the inclined inner surface 41 on the bubble side, eliminates its drooping, and its low wind speed reduces its vibration, thus completely preventing the generation of wavy slack on the surface of the bubble B. can do. The air that has flowed into the dent 46 and temporarily stayed therein is agitated in the dent 46 by the cooling airflow that is blown out from the lower outlet 30 of the air ring 32, and a part of the air flows sequentially along the bubble. , And flows out from the dent 46 toward the upper outlet 31 side, so that the air in the dent 42 can be always kept at a low temperature.

The velocity of the cooling air flow blown out from the lower outlet 30 is rapidly reduced by the flow of the air flow into each of the depressions 42, and the flow velocity is further reduced by the mixing and extrusion of the air from the depressions 42. Also, the speed of the air flow in the gap between the outer surface of the bubble B and the tip surface of the outer lip 33 of the lower outlet 30 is also reduced, and the degree of the Venturi effect generated by this air flow is not increased so much. The bubble B does not have a risk of coming into contact with the tip surface of the outer lip 33, so that there is no possibility that the wall B will be unevenly molded.

The air flowing out to the upper outlet 31 merges with the air blown out from the upper outlet 31 to further cool the bubbles and to regulate the pressure.
6, the blowing ratio is increased by the auxiliary bubble guide body 39 while the outside air flow which is supported from the outside, gradually expands, and is then sucked into the cylindrical body 37 is blown from the chamber 38 toward the bubble B, so that the bubble is stabilized. Then, the resin can be stably formed at a high blow ratio with a wide width and substantially the same stretching ratio in the vertical and horizontal directions without a part of the bubble coming into contact with the auxiliary lip 35.

Further, the cooling air flow supplied from the blower P flows through the block
And the cooling air flow supplied to the upper outlet 31 through the vertical annular air passage 45 formed on the outer surface of the block body 40 on the side opposite to the bubble. Near the lower end of the annular air passage 45, after rectifying and adjusting the pressure in the horizontal annular air passage 46 diverging toward the block body 40, a cooling air flow having a constant pressure is supplied from the entire area of the upper outlet 31. It is possible to stably support and blow the entire circumference of the bubble B and the bubble B, thereby reducing the pressure loss. When the blow ratio is changed, the capacity of the rectification pressure adjusting chamber 36 can be changed by changing the height of the auxiliary lip 35 in accordance with the blow ratio, and the air blowing amount from the chamber 38 can be changed. When adjusting the position of the auxiliary bubble guide body 39 or increasing the opening area of the chamber 38, the position of the auxiliary bubble guide body 39 can be adjusted in the vertical direction. In the above-described example, an example in which the extruder A is connected to an inflation molding die is described. However, the present invention does not change even if the extruder A is connected to a blow molding die or a flat T die.

[Brief description of the drawings]

FIG. 1 is a schematic front view showing a screw of an extruder in an embodiment.

FIG. 2 is a schematic plan view showing a relationship between a hopper gland area and a screw of the extruder of FIG.

FIG. 3 is a half sectional vertical end view showing this use state.

FIG. 4 is a sectional view showing a hopper ground area of the cylinder in FIG. 2;

[Explanation of symbols]

 11 1st screw 12 2nd screw 13 Separation part

Claims (9)

[Claims] An extrusion molding machine, wherein a screw of a screw in a hopper gland region of a cylinder has a tapered portion whose groove depth becomes shallower from a rear end to a front end of the hopper gland region. Molding machine. 2. The length of the screw in the hopper ground area is at least three pitches from the center position of the hopper.
2. A groove according to claim 1, wherein the groove depth of the pitch is the same, and the groove depth of the remaining one pitch is formed in a taper that becomes shallower as going forward from the groove depth of the two pitches. Extrusion molding machine. 3. The extruder according to claim 1, wherein the screw includes a supply section, a melting promoting section, a homogenizing section, and a measuring section from the hopper gland area of the cylinder to a discharge port of the extruding machine. A first screw is formed at a central portion of the first screw, and a second screw having a smaller pitch than the pitch of the first screw is formed in the remaining portion of the fusion promoting portion. The second screw is separated by a predetermined distance, and a kneading portion is formed at the separated portion. The first screw is located at the supply portion corresponding to the hopper gland region and at the melting promoting portion near the separated portion. The groove depth of the middle part is formed to be shallower than the groove depth to be formed, and the groove depth of the communicating part between the deep part of the groove depth and the remaining part is tapered. The extrusion molding according to claim 1 or 2, . 4. The length of the first screw is at least 13 pitches from the center of the hopper, and three pitches of the 13 pitches are located from the center of the hopper corresponding to the hopper grant area. The groove depth of two pitches from the center position of the hopper is constant,
The groove depth of the pitch is formed in a taper that becomes shallower as it goes forward from the groove depth of the two pitches, and the groove depth of the two pitches following the tapered portion is the groove of the two pitches from the center position of the hopper. Shallower than depth, constant
The two-pitch groove depth following the shallow part of the groove depth is formed in a taper that gradually becomes deeper forward, and the remaining five-pitch groove depth following the tapered part is:
4. The extruder according to claim 3, wherein the extruder is formed so as to be equal to or slightly deeper from the hopper center position by two pitches. 5. In the first screw, a ratio h / D of each groove depth h to a screw diameter D is a portion located in the melting promoting portion on the side of the supply portion corresponding to the hopper gland region and the separation portion. 5. The extrusion molding machine according to claim 3, wherein the ratio h / D in the intermediate portion is 0.09 to 0.093. 6. 6. The extruder according to claim 3, wherein a ratio of a pitch of the second screw to a pitch of the first screw is 0.77 to 0.85. 7. The extruder according to claim 3, wherein the size of the separated portion is 8 to 10 mm. 8. The screw diameter is 50 mm to 90 mm.
The extruder according to claim 3, 4, 5, 6, or 7. 9. A spiral groove having the same pitch as a pitch of a first screw of the screw, and a spiral groove is formed in the hopper ground area in a reverse screw relation to the first screw. 9. A forced cooling zone, and a barrel portion located in the vicinity of the hopper gland in the direction of transport of the pellets is a natural cooling zone. The extruder as described.